Good idea on the fermentation.
I think it's fun experimenting with different fats in general recipes. I once used duck fat in place of butter in hollandaise, and it was wonderful over poultry. Bacon fat mayo might be good over tomatoes. Kitchen as laboratory!
"Right is right, even if no one is doing it; wrong is wrong, even if everyone is doing it." - St. Augustine
Who says back fat is a bad thing? Maybe on a hairy guy at the beach, but not on a crab.
Flavor has a slight porky taste, I think it will work great for the recipe I have in mind.